[The influence of exogen and endogen factors on the moulting of Pygnogonum litorale (Ström)].

Pycnogonum litorale has a terminal anecdysis. After attaining maturity it does not moult again. Maturity can be attained at different body size, the female usually being larger than the male.The pre-adult instar can also be entered at various body sizes. The duration of the pre-adult instar depends upon body size: At 19°C its mean duration was 86 days, that of the preceding instar 71 days.The freshly moulted animal is transparent. It feeds soon after each moult, which is essential for hardening the integument. Hardening and stretching of the integument continue for about three weeks.Photoperiods differing from those at which the animal was collected, delay moulting. Long day favours adult development.Temperatures of 2-3° C block the moults.The adult moult is not so easily influenced by these factors as the juvenile moults. Possibly a critical phase aster which moulting can no longer be prevented occurs sooner during the pre-adult instar than in earlier instars.After loss of leg parts the rest of the leg is not automomized. The limbs of juvenile animals regenerate at the following moult. Moulting is not accelerated but rather delayed.With Ecdyson and Ecdysterone moults have not yet been evoked.